The invention proposes an indicator light in particular for a motor vehicle.
The invention proposes more particularly an indicator light, in particular for a motor vehicle, of the type comprising a central optical axis oriented from rear to front, a light source roughly at one point disposed on this optical axis, and a solid optical piece, at least partly of revolution about the optical axis, which is produced from a transparent material with a refractive index greater than that of air and which is arranged at the front of the source, of the type in which the optical piece comprises at least:
an input face whose generatrix lies in a direction substantially parallel to the optical axis;
a rear reflection face whose generatrix lies in a direction substantially inclined towards the front;
and a front exit face;
so that the light flux emitted by the source and entering the optical piece through the inlet face is reflected on the rear reflection face, according to the principal of total reflection, and is returned towards the front exit face in a direction roughly parallel to the optical axis, with a view to fulfilling a given indicating function.
This type of indicator light is already known, in particular through the document FR-A-2.507.741 and fulfils the indicating functions which are defined by current regulations.
The indicating functions of a vehicle light must comply with regulations which define specific photometric conditions for each indicating function to be performed.
For example, according to the regulations currently in force in Europe, an indicator light fulfilling a fog light function must form, on the measuring screen placed at ten meters, an image which has roughly a diamond shape.
This diamond is defined by characteristic points which are arranged on the measuring screen and which must each receive a light intensity whose value must be in a given range.
In the same way, an indicator light fulfilling a reversing light function must form, on the measuring screen, a rectangle of given dimensions whose length is parallel to the horizontal plane.
An indicator light of the type described in the document FR-A-2.507.741 generally requires several optical pieces for fulfilling the required indicating function. For example, a first optical piece, or flux recoverer, is provided for recovering the light flux emitted by the source and concentrating it on the rear face of a second optical piece, or flux diffuser, which is placed axially at the front of the flux recoverer.
The flux diffuser is designed to spatially distribute the light flux forwards so as to form a light beam whose image, on a measuring screen placed at ten meters, matches the image of the function to be fulfilled, for example a diamond for a fog light function according to European regulations or a horizontally stretched rectangle for a reversing light function.
The invention aims in particular to reduce the number of parts necessary for fulfilling a given indicating function and to reduce the size of the indicator light.
For this purpose, the invention proposes an indicator light of the type described above, characterised in that
the exit face is formed by a series of elementary distribution dioptric elements, each of which is designed to form an elementary light beam whose image, on a screen placed in front of the indicator light, corresponds to the indicating function to be fulfilled.
According to other characteristics of the invention:
each elementary dioptric element extends roughly in a radial plane, and the elementary dioptric elements form a mesh;
the dioptric elements are arranged in rings around the optical axis, and each dioptric element extends over an angular ring portion;
the optical piece comprises several rear reflection faces which are stepped axially and radially;
the optical piece comprises several entry faces which are stepped axially towards the rear and radially from the optical axis towards the outside;
the optical piece comprises a central portion, at least partly of revolution about the optical axis, which is arranged axially to the front of the light source and which comprises at least one rear entry face which is designed to divert the incoming light flux, according to the refraction principle, in order to return it, in a direction substantially parallel to the optical axis, to a central front exit face associated with the optical piece, designed to form a light beam corresponding to the indicating function to be fulfilled;
at least one part of the central portion is a lens;
the optical piece comprises a substantially cylindrical rear housing coaxial with the optical axis in which the light source is arranged;
the optical piece comprises several annular rear reflection faces which are stepped axially towards the front and radially from the optical axis towards the outside, two adjacent rear reflection faces being separated by an optically neutral annular rear face arranged outside the path of the light flux which has just been reflected on the said rear reflecting faces;
the optical piece comprises several annular front exit faces which are stepped axially towards the front and radially from the optical axis towards the outside;
the rear face of the optical piece has roughly the shape of a spherical cap centred on the optical axis;
the light source is a light-emitting diode;
the optical piece is produced in a single piece, in particular by plastic moulding.
Other characteristics and advantages of the invention will emerge from a reading of the following detailed description, for an understanding of which reference will be made to the accompanying drawings, amongst which: